Method of manufacturing outer cutter of rotary electric shaver

ABSTRACT

A method of manufacturing an outer cutter of a rotary electric shaver that includes the outer cutter and an inner cutter which is slidingly in contact with a bottom surface of the outer cutter and rotates, in which a plurality of the circular shaving surfaces are integrally formed in the outer cutter in a concentric manner, and round hole-shaped hair introduction openings are formed in at least one of the circular shaving surfaces includes (a) a step of grinding or polishing a predetermined position where the round hole-shaped hair introduction openings are formed in the circular shaving surface to obtain a thickness size smaller than an inner diameter size of the round hole; and (b) a step of forming the round hole-shaped hair introduction openings in the position where the grinding or the polishing is performed by pressing, after the step (a).

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of theprior Japanese Patent Application No. P2012-267414, filed on Dec. 6,2012, and the entire contents of which are incorporated herein byreference.

FIELD

The present invention relates to a method of manufacturing an outercutter of a rotary electric shaver, more specifically a method ofmanufacturing an outer cutter of a rotary electric shaver that has roundhole-shaped hair introduction openings on a circular shaving surface ofthe outer cutter.

BACKGROUND

A rotary electric shaver that includes an outer cutter which has acircular shaving surface as a top surface where numerous hairintroduction openings are formed; an inner cutter which has a smallcutter slidingly in contact with a bottom surface of the outer cutterfrom below the shaving surface and rotates, and in which a plurality ofcircular shaving surfaces are integrally formed on the outer cutter in aconcentric manner has been known (refer to PTL 1 and PTL 2).

CITATION LIST Patent Literature

-   PTL 1: JP-A-2012-100728-   PTL 2: JP-A-2010-528801

SUMMARY Technical Problem

Here, since an outer cutter of a rotary electric shaver that isdescribed in JP-A-2012-100728 is configured to include slit-shaped hairintroduction openings only which are provided side by side at smallintervals, there is a small plane surface area (hereinafter, referred toas a “sliding surface portion”) including no hair introduction opening,thereby having a problem of leaving unpleasant feeling on skin.

Meanwhile, since an outer cutter of a rotary electric shaver that isdescribed in JP-A-2010-528801 is provided with the round hole-shapedhair introduction openings in addition to the slit-shaped hairintroduction openings, the sliding surface portion can be expected to bewidened as an effect. However, in the related art, the aforementionedouter cutter that includes the round hole-shaped hair introductionopenings is essentially manufactured by an electric discharging method,an electrolytic processing method, a laser processing method, and anetching method. Therefore, a manufacturing method is upgraded andcomplicated, and a period in a manufacturing step is prolonged, therebyhaving a problem of an increase in manufacturing cost.

The present invention has been made in consideration of theabove-describe circumstances. The invention has an object to provide amanufacturing method in which an outer cutter of a rotary electricshaver that has round hole-shaped hair introduction openings on acircular shaving surface can be easily and inexpensively formed, and inwhich the outer cutter that feels pleasant on skin can be formed.

Solution to Problem

As an exemplary embodiment, a below-disclosed means solves the problems.

A disclosed method of manufacturing an outer cutter of a rotary electricshaver includes the outer cutter which has a circular shaving surface asa top surface where numerous hair introduction openings are formed andincludes an inner cutter which has a small cutter slidingly in contactwith a bottom surface of the outer cutter from below of the shavingsurface and rotates, in which a plurality of circular shaving surfacesare integrally formed in the outer cutter in a concentric manner, andround hole-shaped hair introduction openings are formed in at least oneof the circular shaving surfaces includes (a) a step of grinding orpolishing a predetermined position where the round hole-shaped hairintroduction openings are formed on the circular shaving surface toobtain a thickness size smaller than an inner diameter size of the roundhole; and (b) a step of forming the round hole-shaped hair introductionopenings in the position where the grinding or the polishing isperformed by pressing, after the step (a).

Advantageous Effects of Invention

According to the disclosed method of manufacturing an outer cutter of arotary electric shaver, it is possible to easily and inexpensively formround hole-shaped hair introduction openings on a circular shavingsurface of the outer cutter of the rotary electric shaver. Since asliding surface portion can be widened by forming the round hole-shapedhair introduction openings in the circular shaving surface, it ispossible to form an outer cutter that feels pleasant on skin.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view (perspective view) illustrating an example ofa rotary electric shaver according to an embodiment of the presentinvention.

FIG. 2 is a schematic view (plan view) illustrating an example of therotary electric shaver illustrated in FIG. 1.

FIG. 3 is a schematic view (cross-sectional view of a side surface)illustrating an example of the rotary electric shaver illustrated inFIG. 2.

FIG. 4 is an explanatory diagram that describes a method ofmanufacturing the outer cutter of the rotary electric shaver illustratedin FIG. 2.

FIG. 5 is an explanatory diagram that describes the method ofmanufacturing the outer cutter of the rotary electric shaver illustratedin FIG. 2.

FIG. 6 is an explanatory diagram that describes the method ofmanufacturing the outer cutter of the rotary electric shaver illustratedin FIG. 2.

FIG. 7 is the explanatory diagram that describes the method ofmanufacturing the outer cutter of the rotary electric shaver illustratedin FIG. 2.

FIGS. 8A and 8B are explanatory diagrams to describe the method ofmanufacturing the outer cutter of the rotary electric shaver illustratedin FIG. 2.

FIG. 9 is an explanatory diagram to describe the method of manufacturingthe outer cutter of the rotary electric shaver illustrated in FIG. 2.

FIG. 10 is an explanatory diagram to describe the method ofmanufacturing the outer cutter of the rotary electric shaver illustratedin FIG. 2.

FIG. 11 is a schematic view (plane view) illustrating another example ofthe outer cutter of the rotary electric shaver according to theembodiment of the invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, referring to views, an embodiment of the present inventionwill be described in detail. FIG. 1 is a perspective view (schematicview) illustrating an example of a rotary electric shaver 1 according toan embodiment of the invention. FIG. 2 is a plan view (schematic view)of an outer cutter 10A of the rotary electric shaver 1. FIG. 3 is across-sectional view of a side surface (schematic view) of the outercutter 10A. In all views for describing the embodiment, the samereference numerals are applied the members that have the same functions,and descriptions thereof may not be repeated.

According to an aspect of the invention, as illustrated in FIGS. 1 to 3,there is provided the rotary electric shaver 1 that includes the outercutter 10A which has a shaving surface (below-described circular shavingsurface) as a top surface where numerous hair introduction openings areformed and includes an inner cutter 12A which has a small cutterslidingly contacting a bottom surface of the outer cutter 10A from belowof the shaving surface and rotates. The rotary electric shaver cuts hairthat enters hair introduction openings with the outer cutter 10A and theinner cutter 12A. The rotary electric shaver that has three sets of acombination of the outer cutter 10A and the inner cutter 12A will beexemplified for description, without being limited thereto.

In FIG. 1, the reference numeral 50 is a main body portion that has acase 54 of which an upper portion of a substantially cylindrical-shapedgrip portion 52 is bent in an obliquely front-upward manner. The case 54is split into two, and a rechargeable battery, an electric motor, and acontrol circuit substrate (not illustrated) are contained insidethereof. A power switch 56 is attached to a front surface of the case54, and a display portion (not illustrated) that is configured to havean LED lamp illustrating a remaining capacity of the battery and anoperation state is provided below the switch 56.

A head portion 58 is openably and detachably attached in an upperportion of the case 54. The head portion 58 is tilted with respect tothe grip portion 52 of the case 54 so as to direct the shaving surface(below described top surface of cutter frame body 60) thereof in theobliquely front-upward manner. A rotation output shaft of the electricmotor protrudes from the upper portion of the case 54 toward an insideof the head portion 58 to rotationally drive the inner cutter 12A, andelastically pushes the inner cutter 12A upward, thereby appropriatelymaintaining contact pressure with respect to a bottom surface of shavingsurfaces 16A and 18A of small cutters 22A and 24A.

The head portion 58 has a configuration in which three sets of a cutterassembly body 62 are installed in the cutter frame body 60 that isopenably attached to the top surface of the case 54. The cutter framebody 60 has a substantially triangle shape in a plan view and of which aperipheral edge is in a shape that is smoothly curved downward. Threecircular mounting ports are formed in the cutter frame body 60, and thecutter assembly bodies 62 are respectively and tiltably held upward witha resetting habit in a movable manner.

That is, the cutter assembly body 62 includes the substantiallydisc-shaped outer cutter 10A of which a peripheral edge is bentdownward, an outer cutter rim 64 into which the outer periphery of theouter cutter 10A is fit (refer to FIG. 1), and the inner cutter 12A thatis slidingly in contact with the outer cutter 10A from below (refer toFIG. 3). The inner cutter 12A is rotatably held in the cutter assemblybody 62 so as not to fall off downward, thereby being rotatably drivenby the electric motor as described above.

Here, a plurality of circular shaving surfaces are integrally formed inthe outer cutter 10A in a concentric manner. In the embodiment, asillustrated in FIGS. 2 and 3, two (dual) of the circular shavingsurfaces 16A and 18A that are concentric with a center shaft 20A, and acircular concave groove 14A that is located therebetween are formed onthe outer cutter 10A. However, without being limited to theconfiguration, the configuration may have three or more of the circularshaving surfaces and two or more of the circular concave grooves (notillustrated).

As an example, in the circular shaving surfaces 16A and 18A, thecircular shaving surface 18A on an inner side is higher than thecircular shaving surface 16A on an outer side, that is, the closer tothe center shaft 20A, the higher in a height. The circular shavingsurfaces 16A and 18A are configured to be located on a horizontal planewith respect to the center shaft 20A (refer to FIG. 3). However, withoutbeing limited thereto, the circular shaving surfaces 16A and 18A may beformed to be the same in height.

In addition, the numerous hair introduction openings are formed in thecircular shaving surfaces 16A and 18A to have a configuration in whichthe top surface thereof protrudes farther than the outer cutter rim 64.In the embodiment, round hole-shaped hair introduction openings 30 (30 aand 30 b) and slit-shaped hair introduction openings 32 are included ashair introduction openings. Here, the round hole-shaped hairintroduction openings (round holes) 30 are not limited to a truecircular shape, and other circular shapes such as an elliptical shapeand the like are also included. Meanwhile, the slit-shaped hairintroduction openings (slits) 32 are not limited to an oblong shape, andother rectangular shapes such as a trapezoidal shape and the like arealso included.

More specifically, only the slit-shaped hair introduction openings 32are provided in the circular shaving surface 16A at the outermostperiphery. In this way, since the circular shaving surface 16A at theoutermost periphery normally and mostly exhibits an action of capturingand cutting of hair, it is possible to increase an effect of thecapturing and the cutting of hair by arranging only the slit-shaped hairintroduction openings 32 that are highly effective in the capturing ofhair.

In the circular shaving surface other than the outermost periphery (thatis, the circular shaving surface 18A on an inner periphery side in theembodiment), the round hole-shaped hair introduction openings 30 and theslit-shaped hair introduction openings 32 are provided side by side. Inthe embodiment, along a peripheral direction of the circular shavingsurface 18A on the inner periphery side, a round hole forming area 31that consists of a predetermined number of round hole-shaped hairintroduction openings 30 (30 a and 30 b) and a slit forming area 33 thatconsists of a predetermined number of slit-shaped hair introductionopenings 32 are configured to be alternately provided. As an example, asillustrated in FIG. 2, in the circular shaving surface 18A on the innerperiphery side, three round hole forming areas 31 and three slit formingareas 33 are configured to be alternately provided. However, withoutbeing limited thereto, three or more, for example, five round holeforming areas 31 and five slit forming areas 33 may be configured to bealternately provided as illustrated in a modification example of FIG.11. Furthermore, it is not limited to a case in which the round holeforming area 31 and the slit forming area 33 are not the same in number.

The slit-shaped hair introduction openings 32 are highly effective inthe capturing and the cutting of hair. On the other hand, there is aproblem of leaving unpleasant feeling on skin. However, as in theembodiment, if a configuration is obtained in which only the slit-shapedhair introduction openings 32 are provided in the circular shavingsurface 16A at the outermost periphery, and the round hole-shaped hairintroduction openings 30 (30 a and 30 b) and the slit-shaped hairintroduction openings 32 are provided side by side in the circularshaving surface 18A other than at the outermost periphery, the area ofthe sliding surface portion 34 can be increased without beingdeteriorated in a function of the capturing hair. Accordingly, it ispossible to realize the outer cutter that feels pleasant on skin.Furthermore, it is possible to enhance the intent to purchase byproviding a novel design to a user through the configuration that can befound in the related art, that is, the round hole forming area 31 andthe slit forming area 33 are alternately disposed.

Here, the round hole-shaped hair introduction openings 30 are formed tohave the round holes 30 a at the inner periphery side and the roundholes 30 b at the outer periphery side that are alternately disposed ina zigzag manner along the peripheral direction of the circular shavingsurface 18A. In the embodiment, as illustrated in FIG. 2, in one roundhole forming area 31, the round holes 30 a at the inner periphery sideand the round holes 30 b at the outer periphery side that are formed tobe alternately disposed in a zigzag manner along the peripheraldirection of the circular shaving surface 18A, such as the roundhole-shaped hair introduction opening (round hole at the outer peripheryside) 30 b, the round hole-shaped hair introduction opening (round holeat the inner periphery side) 30 a, the round hole-shaped hairintroduction opening (round hole at the outer periphery side) 30 b, theround hole-shaped hair introduction opening (round hole at the innerperiphery side) 30 a, and so forth to the round hole-shaped hairintroduction opening (round hole at the outer periphery side) 30 b.

In this way, it is possible to form the round hole-shaped hairintroduction openings 30 (30 a and 30 b) by a shearing press processingthat has been difficult hitherto. That is, when the round hole-shapedhair introduction openings are provided side by side on the same radius,in order to improve the function of the capturing hair, it is requiredto make intervals of the adjacent round hole-shaped hair introductionopenings be close to each other at a predetermined distance (forexample, clearance of approximately 0.2 mm). However, if the roundhole-shaped hair introduction openings are set in the aforementionedintervals, pins of a punch for the shearing press processing are tooclose to each other, and a pin diameter becomes too thin, thereby beingdifficult to perform the shearing press processing. In contrast, as inthe embodiment, through the configuration in which the round holes 30 aat the inner periphery side and the round holes 30 b at the outerperiphery side are formed to be alternately disposed in a zigzag manner,a processing method can be employed in which the shearing pressprocessing is performed on a plurality of round holes (that is, eitherone of only the round hole 30 a at the inner periphery side or only theround hole 30 b at the outer periphery side in one round hole formationarea 31) that are disposed at one of the inner periphery side or theouter periphery side by a single press, and then, the shearing pressprocessing is performed to the round holes (that is, the other one ofonly the round hole 30 a at the inner periphery side or only the roundhole 30 b at the outer periphery side in one round hole formation area31) that are disposed at the other one of the inner periphery side orthe outer periphery side by the single press. In this way, it ispossible to make the round hole-shaped hair introduction openings (roundholes at the inner periphery side) 30 a and the round hole-shaped hairintroduction openings (round holes at the outer periphery side) 30 bthat are adjacent in the zigzag manner be close to each other at apredetermined distance (for example, clearance of approximately 0.2 mm).In addition, the intervals of the round hole-shaped hair introductionopenings that are side by side in the same radius (interval between oneround hole 30 a and a round hole 30 a next thereto, and interval betweenone round hole 30 b and a round hole 30 b next thereto) can be separatedby a distance (for example, clearance of approximately 0.3 mm to 0.4 mm)that allows the shearing press processing. That is, regarding the punchfor forming the round hole-shaped hair introduction openings 30 (30 aand 30 b), two types of punches, one for round hole processing of theinner periphery side and another for the round hole processing of theouter periphery side, are prepared. Therefore, in each punch, it ispossible to separate apart the distance between the adjacent pins in thesame radius farther than a predetermined distance, and it is possible tosecure strength by having the pin diameter at a predetermined thickness,and the round hole-shaped hair introduction openings 30 (30 a and 30 b)can be formed through the shearing press processing.

Meanwhile, as illustrated in FIG. 3, the inner cutter 12A has aconfiguration in which the small cutters 22A and 24A that are slidinglyin contact with the bottom surfaces (inner cutter sliding surfaces) 16Band 18B of the shaving surfaces 16A and 18A are integrally formed with acommon metal plate 12B. Since the upper end edge of the small cutters22A and 24A are slidingly in contact with the bottom surfaces 16B and18B that respectively become the inner cutter sliding surfaces, and cutshair that enters the round hole-shaped hair introduction openings 30 (30a and 30 b) and the slit-shaped hair introduction openings 32, it isnecessary that the upper end edge has a uniform height as the height ofthe inner cutter sliding surfaces 16B and 18B and the upper end edge ispolished to be improved in sharpness of a cutter.

Subsequently, the method of manufacturing the outer cutter of the rotaryelectric shaver 1 will be described according to the embodiment.

Firstly, as illustrated in FIG. 4, a flat plate sheet material made ofstainless steel (as an example, with a thickness of 0.6 mm) is prepared,and punching of a circular plate-shaped member 10Aa having apredetermined diameter is performed by performing the punch against afront surface side through the shearing press processing. At the sametime, a central opening portion 8 is formed by the punching.

Next, as illustrated in FIG. 5, a drawing press processing is performedto the punched circular plate-shaped member 10Aa to press out the areaof the circular shaving surfaces 16A and 18A that are arranged on acircular shape and obtain a stereoscopic shaped member 10Ab by formingthe circular concave groove 14A. The circular shaving surfaces 16A and18A become a so-called cutting edge portion. The circular shavingsurfaces 16A and 18A can be employed either in a case where a height ofeach top surface is the same or in a case where the height of each uppersurface is different.

Here, a cutout portion (hereinafter, referred to as a “D-shaped cutportion”) 9 is formed at the outer periphery edge of a predeterminedposition of the outer cutter (in this case, stereoscopic shaped member10Ab) by punching at the same time with the drawing press processing orthereafter. The D-shaped cut portion 9 is used as a position markdescribed below.

Next, a thickness reduction is performed to the circular shavingsurfaces 16A and 18A of the stereoscopic shaped member 10Ab. Morespecifically, at this moment, since portions that become the circularshaving surfaces 16A and 18A have a thickness of a metal plate in theirintegrity (as an example, with a thickness of 0.6 mm), the thicknessreduction of the circular shaving surfaces 16A and 18A is performeduntil a predetermined thickness is obtained by performing the grindingor the polishing of the parts that become the circular shaving surfaces16A and 18A. In the embodiment, the grinding or the polishing of thecircular shaving surfaces 16A and 18A is performed so as to obtain avalue in thickness size (as an example, with a thickness of 0.2 mm)smaller than an inner diameter size (as an example, inner diameter of0.3 mm to 0.6 mm) of the round hole-shaped hair introduction openings(described below) that are formed on the circular shaving surfaces 16Aand 18A during a post-processing. By including the processing in thepost-processing, it is possible to form the round hole-shaped hairintroduction openings that have a suitable inner diameter (as anexample, inner diameter 0.3 mm to 0.6 mm) for capturing hair on thecircular shaving surfaces 16A and 18A by the shearing press processing.However, in consideration of the thickness reduction, it is important toemploy the shearing press processing method described below.

Here, as illustrated in FIG. 6, the thickness reduction can be performedby rotating a grinding tool 72 such as a turning tool or a polishingtool such as a whetstone (here, both may be collectively referred to asa grinding/polishing tool) of which the top surface corresponds to theheight of the circular shaving surfaces 16A and 18A about the centershaft 20A.

Similarly, the bottom surface of the circular shaving surfaces 16A and18A use a grinding/polishing tool 74 that corresponds to the heightsthereof to be rotated about the center shaft 20A, thereby enabling theprocessing. The reference numerals 16A and 18A that are illustrated withdashed lines in FIG. 6 denote the top surface of the shaving surfaces(surfaces contacting skin), and the reference numerals 16B and 18Bdenote the bottom surface of the shaving surfaces (surface where thesmall cutters 22A and 24A of the inner cutter 12A slides, inner cuttersliding surface). In place of rotating the grinding/polishing tools 72and 74 or together with the rotating of the same, as a matter of course,the outer cutter 10A may be rotated.

Next, as illustrated in FIG. 7, forming of the round hole-shaped hairintroduction openings 30 is performed at a position where the thicknessreduction (grinding or polishing) is performed on the circular shavingsurfaces 16A and 18A by the shearing press processing. Morespecifically, with respect to the circular shaving surfaces 16A and 18Aof the stereoscopic shaped member 10Ab, a rear surface side (surface tobe the bottom surface side) is supported by a die, the punch is pressedagainst the front surface side (surface to be the top surface), adrilling is performed from the front surface side toward the rearsurface side by the shearing press processing, and then, the pluralityof round hole-shaped hair introduction openings (round holes) 30 (30 aand 30 b) are formed. At this time, the D-shaped cut portion 9 is usedas the position mark that becomes a standard position for a processingto perform the processing of the stereoscopic shaped member 10Ab,thereby performing the shearing press processing. Accordingly, the roundhole-shaped hair introduction openings (round holes) 30 (30 a and 30 b)can be formed in a predetermined position of the circular shavingsurfaces 16A and 18A which have the D-shaped cut portion 9 as thestandard.

According to the above-described step, it is possible to form the roundhole-shaped hair introduction openings (round holes) 30 (30 a and 30 b)that have a suitable size (as an example, inner diameter of 0.3 mm to0.6 mm) for capturing hair by the shearing press processing. Therefore,compared to a drilling method by the electric discharging method, theelectrolytic processing method, a laser processing method, and theetching method in the related art, the manufacturing method becomeseasy, the manufacturing period can be shortened, and the manufacturingcost can be reduced. Furthermore, since the bottom surface of the outercutter 10A (more specifically, a lower edge portion of the round hole30) that is slidingly in contact with the inner cutter 12A can besharply formed by performing the shearing press processing from thefront surface side (top surface side) toward the rear surface side(bottom surface side), it is possible to obtain the sharpness of thecutter for hair.

In addition, a method of performing the shearing press processing fromthe rear surface side (bottom surface side) toward the front surfaceside (top surface side) may be employed. In this way, it is possible tocause burrs in the shearing press processing to be generated on thefront surface side (top surface side), not on the rear surface side(bottom surface side) where it is difficult for the burrs to be removed.In this way, it is possible to remove the burrs by an easy surfacetreating. In addition, since the bottom surface of the outer cutter 10A(more specifically, lower end portion of the round hole 30) that isslidingly in contact with the inner cutter 12A can be formed in aburr-less shape, it is possible to obtain the sharpness of the cutterfor hair.

Here, in the embodiment, the round hole-shaped hair introductionopenings 30 are formed in the zigzag manner in which the round holes 30a at the inner periphery side and the round holes 30 b at the outerperiphery side are alternately disposed along the peripheral directionof the circular shaving surface 18A. To be specific, in a descriptionreferring to FIG. 8 that is an enlarged view of the C portion in FIG. 7,as the processing at this moment, the shearing press processing isperformed to the plurality of round holes (as an example, as illustratedin FIG. 8A, only the round hole 30 a at the inner periphery side in oneround hole formation area 31) that are disposed at one of the innerperiphery side or the outer periphery side by a single press, and then,the shearing press processing is performed to the round holes (as anexample, as illustrated in FIG. 8B, only the round hole 30 b at theouter periphery side in one round hole formation area 31) that aredisposed at the other one of the inner periphery side or the outerperiphery side by the single press. In this way, as described above, twotypes of punches, one for the round hole processing of the innerperiphery side and another for the round hole processing of the outerperiphery side, are prepared. Therefore, in each punch, it is possibleto separate the distance between the adjacent pins in the same radiusfarther than a predetermined distance, and it is possible to secure thestrength by having the pin diameter at a predetermined thickness, andthe round hole-shaped hair introduction openings 30 (30 a and 30 b) canbe formed through the shearing press processing.

Thereafter, it is suitable to perform a quenching to the stereoscopicshaped member 10Ab.

Next, as illustrated in FIG. 9, a step is performed in which theslit-shaped hair introduction openings 32 are formed at a predeterminedposition of the circular shaving surface by grinding. At this time, theD-shaped cut portion 9 is used as the position mark that becomes thestandard position for a processing to perform the processing of thestereoscopic shaped member 10Ab, thereby performing the grinding.Accordingly, the slit-shaped hair introduction openings (slits) 32 canbe formed in a predetermined position of the circular shaving surfaces16A and 18A which have the D-shaped cut portion 9 as the standard. Thatis, since the D-shaped cut portion 9 is used as the common processingstandard position in the above-described shearing press processing andthe grinding, the round hole-shaped hair introduction openings (roundholes) 30 and the slit-shaped hair introduction openings (slits) 32 thatare respectively formed in different steps can be formed in apredetermined position without occurrence of a position gap.

Here, the grinding of the slit-shaped hair introduction openings 32 areperformed using a rotation disc whetstone 66 as illustrated in FIG. 10.That is, with respect to the stereoscopic shaped member 10Ab thatbecomes the outer cutter 10A, the rotation disc whetstone 66 is rotatedfrom above having the outer periphery thereof vertically oriented andmoved in a substantially radial direction, thereby providing cuts in aportion that becomes the circular shaving surfaces 16A and 18A excludingthe circular concave groove 14A. The rotation disc whetstone 66 is athin circular disc-shaped tool that is made of wear resistant particlessuch as diamond particles which are dispersed in abrasive grains to becured.

More specifically, the processing is firstly performed to both thecircular shaving surfaces 16A and 18A at the same time, a processing ina depth along a first processing line 68 in FIG. 10 by the rotation discwhetstone 66 is performed. That is, a rotational center A of therotation disc whetstone 66 is moved in a substantially radial direction(movement line 68 a direction in FIG. 10) such that an outer periphery(cutting edge) of the rotation disc whetstone 66 moves along the firstprocessing line 68. In addition, in order to selectively and deeplyperform processing only to the slits 32 of the circular shaving surface16A on the outside, the rotational center A is moved to a position of Bsuch that the outer periphery of the rotation disc whetstone 66 is movedalong a second processing line 70 that is illustrated in FIG. 10, andthen, the center B is moved in the substantially radial direction alonga movement line 70 a that is parallel to the second processing line 70.

Next, a thickness reduction for finishing is performed to the circularshaving surfaces 16A and 18A of the stereoscopic shaped member 10Ab. Inthe embodiment, the thickness reduction is performed in the previousstep up to the circular shaving surfaces 16A and 18A to obtain a valuein thickness size (as an example, with a thickness of 0.2 mm) smallerthan an inner diameter size (as an example, inner diameter of 0.3 mm to0.6 mm) of the round hole-shaped hair introduction openings (describedbelow). The grinding or the polishing is further performed in thepresent step, and the processing is performed until the circular shavingsurfaces 16A and 18A obtain a predetermined thickness size (as anexample, with a thickness of 0.08 mm). Accordingly, the stereoscopicshaped member 10Ab is formed as the outer cutter 10A. The outer cutter10A obtains the sharpness in cutting which can perform deep shaving.

As described above, in the method of manufacturing the outer cutter ofthe rotary electric shaver according to an aspect of the invention, itis possible to easily and inexpensively form the round hole-shaped hairintroduction openings 30 on the circular shaving surface 18A of theouter cutter 10A by the shearing press processing. In addition, sincethe sliding surface portion 34 can be widened by forming the roundhole-shaped hair introduction openings 30 on the circular shavingsurface 18A, it is possible to form the outer cutter 10A that feelspleasant on skin.

The invention is not limited to the embodiment described above, andvarious modifications and changes can be made without departing from thescope of the invention. Particularly, the rotary electric shaver thathas three sets of the combination of the outer cutter and the innercutter is exemplified for description. However, the invention is notlimited thereto and can also be applied to the r otary electric shaverthat has one set, two sets, four sets or more sets of the combination ofthe outer cutter and the inner cutter.

What is claimed is:
 1. A method of manufacturing an outer cutter of arotary electric shaver that includes the outer cutter which has acircular shaving surface as a top surface where numerous hairintroduction openings are formed and an inner cutter which has a smallcutter slidingly in contact with a bottom surface of the outer cutterfrom below of the shaving surface and rotates, in which a plurality ofthe circular shaving surfaces are integrally formed in the outer cutterin a concentric manner, and round hole-shaped hair introduction openingsare formed in at least one of the circular shaving surfaces, the methodcomprising: (a) a step of grinding or polishing a predetermined positionwhere the round hole-shaped hair introduction openings are formed on thecircular shaving surface to obtain a thickness size smaller than aninner diameter size of the round hole; and (b) a step of forming theround hole-shaped hair introduction openings in the position where thegrinding or the polishing is performed by pressing, after the step (a).2. The method of manufacturing an outer cutter of a rotary electricshaver according to claim 1, wherein the step (b) is performed to formthe round hole-shaped hair introduction openings that include the roundholes at an inner periphery side and the round holes at an outerperiphery side to be alternately disposed in a zigzag manner along aperipheral direction of the circular shaving surface.
 3. The method ofmanufacturing an outer cutter of a rotary electric shaver according toclaim 2, wherein, in the step (b), the pressing is performed to aplurality of round holes that are disposed at one of the inner peripheryside or the outer periphery side by a single press, and then, thepressing is performed to the round holes that are disposed at the otherone of the inner periphery side or the outer periphery side by thesingle press.
 4. The method of manufacturing an outer cutter of a rotaryelectric shaver according to claim 1, further comprising: (c) a step offorming slit-shaped hair introduction openings in a predeterminedposition of the circular shaving surface by the grinding, after the step(b).
 5. The method of manufacturing an outer cutter of a rotary electricshaver according to claim 2, further comprising: (c) a step of formingslit-shaped hair introduction openings in a predetermined position ofthe circular shaving surface by the grinding, after the step (b).
 6. Themethod of manufacturing an outer cutter of a rotary electric shaveraccording to claim 3, further comprising: (c) a step of formingslit-shaped hair introduction openings in a predetermined position ofthe circular shaving surface by the grinding, after the step (b).
 7. Themethod of manufacturing an outer cutter of a rotary electric shaveraccording to claim 4, further comprising: a step of forming a positionmark in a predetermined position of the outer cutter before the step(b), wherein processing is performed in each of the steps (b) and (c)taking the position mark as a common processing standard position. 8.The method of manufacturing an outer cutter of a rotary electric shaveraccording to claim 5, further comprising: a step of forming a positionmark in a predetermined position of the outer cutter before the step(b), wherein processing is performed in each of the steps (b) and (c)taking the position mark as a common processing standard position. 9.The method of manufacturing an outer cutter of a rotary electric shaveraccording to claim 6, further comprising: a step of forming a positionmark in a predetermined position of the outer cutter before the step(b), wherein processing is performed in each of the steps (b) and (c)taking the position mark as a common processing standard position. 10.The method of manufacturing an outer cutter of a rotary electric shaveraccording to claim 7, wherein the position mark is a D-shaped cutportion that is formed at an outer periphery edge of the outer cutter.11. The method of manufacturing an outer cutter of a rotary electricshaver according to claim 8, wherein the position mark is a D-shaped cutportion that is formed at an outer periphery edge of the outer cutter.12. The method of manufacturing an outer cutter of a rotary electricshaver according to claim 9, wherein the position mark is a D-shaped cutportion that is formed at an outer periphery edge of the outer cutter.13. The method of manufacturing an outer cutter of a rotary electricshaver according to claim 4, wherein the round hole-shaped hairintroduction openings and the slit-shaped hair introduction openings areformed to alternately provide a round hole forming area that isconfigured to have a predetermined number of round hole-shaped hairintroduction openings and a slit forming area that is configured to havea predetermined number of slit-shaped hair introduction openings alongthe peripheral direction on a predetermined circular shaving surface byperforming the steps (b) and (c).
 14. The method of manufacturing anouter cutter of a rotary electric shaver according to claim 5, whereinthe round hole-shaped hair introduction openings and the slit-shapedhair introduction openings are formed to alternately provide a roundhole forming area that is configured to have a predetermined number ofround hole-shaped hair introduction openings and a slit forming areathat is configured to have a predetermined number of slit-shaped hairintroduction openings along the peripheral direction on a predeterminedcircular shaving surface by performing the steps (b) and (c).
 15. Themethod of manufacturing an outer cutter of a rotary electric shaveraccording to claim 6, wherein the round hole-shaped hair introductionopenings and the slit-shaped hair introduction openings are formed toalternately provide a round hole forming area that is configured to havea predetermined number of round hole-shaped hair introduction openingsand a slit forming area that is configured to have a predeterminednumber of slit-shaped hair introduction openings along the peripheraldirection on a predetermined circular shaving surface by performing thesteps (b) and (c).
 16. The method of manufacturing an outer cutter of arotary electric shaver according to claim 1, wherein the roundhole-shaped hair introduction openings are formed in the circularshaving surface other than a outermost periphery.
 17. The method ofmanufacturing an outer cutter of a rotary electric shaver according toclaim 2, wherein the round hole-shaped hair introduction openings areformed in the circular shaving surface other than a outermost periphery.18. The method of manufacturing an outer cutter of a rotary electricshaver according to claim 3, wherein the round hole-shaped hairintroduction openings are formed in the circular shaving surface otherthan a outermost periphery.